1. Field of the Invention
The present invention relates to a semiconductor processing system having a plurality of process chambers each for performing a predetermined semiconductor process in a vacuum atmosphere on a target substrate, such as a semiconductor wafer. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
2. Description of the Related Art
In the process of manufacturing semiconductor devices, a wafer is subjected to various semiconductor processes in vacuum atmospheres, such as film formation, e.g., CVD (Chemical Vapor Deposition), etching, oxidation, diffusion, and annealing. When rapid heating is required in these processes, they are performed on the basis of the concept of RTP (Rapid thermal Processing).
Owing to the demands of increased miniaturization and integration of semiconductor devices, the throughput and yield involving these processes need to be increased. In light of this, there is a semiconductor processing system of the so-called cluster tool type, which has a plurality of process chambers for performing the same process, or a plurality of process chambers for performing different processes, connected to a common transfer chamber (for example, Jpn. Pat. Appln. KOKAI Publication No. 2000-208589). With a semiconductor processing system of the cluster tool type, various steps can be performed in series, without exposing a wafer to air.
FIG. 13 is a plan view schematically showing a conventional processing system of the cluster tool type. As shown in FIG. 13, six vacuum process chambers 12 and two cassette chambers 13 are connected to the sidewall of a transfer chamber 11, which has, e.g., an octagonal shape in plan view. In the transfer chamber 11, there is a transfer machine 14 rotatable and movable back and forth, for transferring a target substrate, e.g., a semiconductor wafer (which will be referred to as a wafer) W.
When wafers W are processed, a wafer cassette C is placed in one of the cassette chambers 13. Then, the transfer machine 14 picks up a wafer W out of the cassette C, and transfers the wafer W into one of the process chambers 12. Where all the process chambers 12 are arranged to perform the same process, wafers W are processed in the process chambers 12 in parallel. Where the process chambers 12 are arranged to perform different processes, a wafer W is subjected to a process in one of the process chambers 12, and then is subjected to another process in another of the process chambers 12. After wafers W have undergone all the necessary processes, they are sequentially returned to the cassette C.
Since this processing system uses a transfer chamber common to a plurality of vacuum processes, the installation space needed is less than that required for vacuum process chambers and transfer chambers connected one by one. In addition, a plurality of wafers W can be subjected to the same process in parallel, or a wafer W can be subjected to a plurality of processes in series, thereby attaining a high throughput.